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| author | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-03 09:45:46 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-03 09:47:14 -0700 |
| commit | 8ccb3dcd1f8e80e8702642e1de26541b52f6bb7c (patch) | |
| tree | ad03dadb63ee1fbc70e271b4962b91b376058040 | |
| parent | 63c422afe3739b68bec0b5c42807d1450c951caf (diff) | |
| download | linux-8ccb3dcd1f8e80e8702642e1de26541b52f6bb7c.tar.gz linux-8ccb3dcd1f8e80e8702642e1de26541b52f6bb7c.tar.bz2 linux-8ccb3dcd1f8e80e8702642e1de26541b52f6bb7c.zip | |
x86: Fix booting with "no387 nofxsr"
Jesper Juhl reported that testing the software math-emulation by forcing
"no387" doesn't work on modern CPU's.
The reason was two-fold:
- you also need to pass in "nofxsr" to make sure that we not only don't
touch the old i387 legacy hardware, it also needs to disable the
modern XMM/FXSR sequences
- "nofxsr" didn't actually clear the capability bits immediately,
leaving the early boot sequence still using FXSR until we got to
the identify_cpu() stage.
This fixes the "nofxsr" flag to take effect immediately on the boot CPU.
Debugging by Randy Dunlap
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Jesper Juhl <jesper.juhl@gmail.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | arch/i386/kernel/cpu/common.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c index 2799baaadf45..b2f24d57fddd 100644 --- a/arch/i386/kernel/cpu/common.c +++ b/arch/i386/kernel/cpu/common.c @@ -184,7 +184,16 @@ static void __cpuinit get_cpu_vendor(struct cpuinfo_x86 *c, int early) static int __init x86_fxsr_setup(char * s) { + /* Tell all the other CPU's to not use it... */ disable_x86_fxsr = 1; + + /* + * ... and clear the bits early in the boot_cpu_data + * so that the bootup process doesn't try to do this + * either. + */ + clear_bit(X86_FEATURE_FXSR, boot_cpu_data.x86_capability); + clear_bit(X86_FEATURE_XMM, boot_cpu_data.x86_capability); return 1; } __setup("nofxsr", x86_fxsr_setup); |